In experiments where Townsville stylo (Stylosanthes humilis) was oversown into perennial grass swards dominated by Heteropogon contortus and Bothriochloa bladhii residual stubble reduced the survival of Townsville stylo seedlings. When this stubble was removed, Townsville stylo plants grew to maturity and made up 25 per cent of the dry matter of the sward, an increase of 500 per cent Townsville stylo yield. Frequency of defoliation from 3 to 12 weeks during the growing season had no effect on the proportion of legume in the sward but the yield of all species was less under frequent cutting. Of the two collections of Townsville stylo used, the erect type always gave the highest yield and there was no evidence of an advantage for the prostrate type under frequent cutting. Over a period of three years the erect type invaded plots sown to the prostrate type. The response of Townsville stylo to superphosphate was large whereas that of the perennial native grasses was only slight.